Mahakipawa Hill MSE Wall (Cullen’s Point)
Client: Marlborough Roads Recovery Team (MRRT)
Stakeholders: Marlborough District Council, MRRT, KGA Geotech (design of temporary works), WSP (MSE Wall designer)
Project overview:
This project involved remediating a slipped roadway along Queen Charlotte Drive caused by storms of July 2021 and further damaged by a second weather event in August 2022.
Temporary works were required for slope stability before the main wall construction. This involved the installation of 24 nine-metre-long reinforced concrete piles anchored to 23 ten-metre-long, self-drilling anchors.
The MSE (mechanically stabilised earth) wall and the culvert and spillway were designed by WSP and consisted of:
- Construction of access into site, stockpile and work areas
- Riprap outfall
- Drainage blanket
- Terramesh wall construction
- Gabian baskets and fibre reinforced concrete pads
- Installation of a 1200dia culvert
- Road construction
Challenges
A requirement to maintain a minimum of one lane of traffic during construction added technical challenges to the project as operating areas were already tight in the steep, narrow location. Although a scenic route for many, the road is a crucial link to the outer Sounds for forestry traffic.
Check out the video of the project construction:
This was the largest MSE wall project that any of the team had ever worked on. There are 18 levels of Gabbion in the MSE wall (compared with 8.5 levels on the Whangamoa MSE wall that the team completed in November 2023).
Photos:
Row one: Before (left), culvert placement and traffic management (middle), and site overview (right)
Rows two, three and four: Hand wire work for the Gabbion baskets and rock placement on site
Row four: Hydromulching at the completed site (right)
